In this era of increased environmental awareness, it is becoming less acceptable to simply discard used or spent materials of any kind. The United States alone generates many millions of tons of unrecycled trash every year. Although it is recognized that some materials are not feasibly reclaimable (such as food, medical supplies, and certain metals and plastics), an increasing number of materials are reusable after treating the material and reforming the material into new items.
Because of this, there is an increasing level of pressure to keep as much material as possible out of landfills. Many safely situated landfills and disposal areas near urban areas, in particular, are already filled to capacity or approaching full capacity. Therefore, in order to properly dispose of many items, new disposal sites must be found. In most cases, these new sites are either further away or less desirable than the existing sites. Accordingly, the cost of simply "throwing away" solid waste is increasing, both in terms of monetary expense (to find and ship to more remote locations) and the environment (committing an increasing amount of scarce physical resources to trash).
Although incineration is frequently useful as an alternative to disposing of solid waste items in a landfill or other disposal site, there is also increasing pressure from the environmentally conscious to reduce incineration as a means of disposal. Although incineration can reduce the bulk of materials shipped to disposal, there are other risks. First, incineration causes air pollution. Although sophisticated exhaust scrubbing systems exist to reduce this problem, these systems are frequently expensive and inefficient.
Moreover, although soot, carbon monoxide, carbon dioxide, ozone, nitrous oxides, and sulfur compounds are the typical results of incinerating trash (and the primary constituents of "smog"), these are only a few of the potential by-products of incinerating trash that includes man-made materials, especially polymers. The incineration of such materials can result in the release of potentially toxic materials, which are frequently difficult to control.
Of course, recycling is one possible means of avoiding the problems with landfills and incineration. Effective recycling procedures exist for many materials, including paper, aluminum, glass, and many plastics. However, man-made articles that are fabricated from more than one material are frequently difficult to recycle, as there can be recycling incompatibilities between the materials. For example, a chemical that is useful to dissolve and separate one type of plastic material may have adverse effects on the properties of other materials that are bound to the recycled plastic.
The foregoing difficulties have rendered it difficult to recycle used carpeting with any kind of efficiency. Carpeting frequently consists of two or more layers of backing material, a binding material (such as a glue), a reinforcing web, and a fibrous pile material. These materials are frequently incompatible with each other in a recycling operation. For example, the means used to separate and reuse a layer of the backing material might affect the usefulness of the pile material. Alternatively, a chemical used in the recycling process might dissolve two or more of the components, causing them to intermix and form a blend of the two materials having less desirable properties. The application of heat to melt certain materials can have the same effect.
Several attempts have been made to avoid the problems inherent in recycling a complex man-made item comprising several materials, and to successfully recycle carpet.
U.S. Pat. No. 5,230,473 to Hagguist et al. uses a combination of chemical, heat, and mechanical means to strip and separate the various components from reclaimed carpet. However, the Hagguist system has several disadvantages. It is a complex system that uses a variety of means to separate the materials, and it attempts to separate the various pile and substrate materials while leaving the backing largely intact. Therefore, the Hagguist system can be extremely expensive. Moreover, it uses potentially volatile and toxic chemicals, as well as pressurized water and steam. Finally, the scheme taught by Hagguist has not been found to be feasible or economically practicable, as it requires waste carpet that is in substantially large and flat pieces, and does not produce a level of contamination that is sufficiently low for efficient recycling.
U.S. Pat. Nos. 5,497,949 and 5,518,188 to Sharer employ mechanical means to decompose carpet into its constituent materials. However, the apparatus and method disclosed by the Sharer patents have been found to be inefficient and result in unacceptable levels of contamination between carpet fibers and backing material. Although this problem can be diminished by mixing reclaimed materials with a substantial amount of new or "virgin" material, this is inefficient and should be avoided.
In light of the various shortcomings of prior attempts to effectively recycle spent carpeting, a need is recognized for a system and method capable of effectively and efficiently separating the constituent materials of used carpeting, so that those materials can be effectively recycled into new product with a minimum of discarded material and a minimum need to add virgin material to reduce contamination levels.
A further need is recognized for a scheme that makes effective and efficient use of the reclaimed materials in new carpeting. The need for virgin material should be kept to a minimum, in order to decrease costs and increase the amount of old material that is converted into new carpeting.